Problem: $-3ij - j - 8k + 7 = j + 4k + 9$ Solve for $i$.
Explanation: Combine constant terms on the right. $-3ij - j - 8k + {7} = j + 4k + {9}$ $-3ij - j - 8k = j + 4k + {2}$ Combine $k$ terms on the right. $-3ij - j - {8k} = j + {4k} + 2$ $-3ij - j = j + {12k} + 2$ Combine $j$ terms on the right. $-3ij - {j} = {j} + 12k + 2$ $-3ij = {2j} + 12k + 2$ Isolate $i$ $-{3}i{j} = 2j + 12k + 2$ $i = \dfrac{ 2j + 12k + 2 }{ -{3j} }$ Swap the signs so the denominator isn't negative. $i = \dfrac{ -{2}j - {12}k - {2} }{ {3j} }$